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/*-------------------------------------------------------------------------
*
* geqo_paths.c--
* Routines to process redundant paths and relations
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: geqo_paths.c,v 1.17 1999/02/12 05:56:48 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "nodes/pg_list.h"
#include "nodes/relation.h"
#include "nodes/primnodes.h"
#include "utils/palloc.h"
#include "utils/elog.h"
#include "optimizer/internal.h"
#include "optimizer/paths.h"
#include "optimizer/pathnode.h"
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/geqo_paths.h"
static List *geqo_prune_rel(RelOptInfo *rel, List *other_rels);
/*
* geqo-prune-rels--
* Removes any redundant relation entries from a list of rel nodes
* 'rel-list'.
*
* Returns the resulting list.
*
*/
List *
geqo_prune_rels(List *rel_list)
{
List *temp_list = NIL;
if (rel_list != NIL)
{
temp_list = lcons(lfirst(rel_list),
geqo_prune_rels(geqo_prune_rel((RelOptInfo *) lfirst(rel_list),
lnext(rel_list))));
}
return temp_list;
}
/*
* geqo-prune-rel--
* Prunes those relations from 'other-rels' that are redundant with
* 'rel'. A relation is redundant if it is built up of the same
* relations as 'rel'. Paths for the redundant relation are merged into
* the pathlist of 'rel'.
*
* Returns a list of non-redundant relations, and sets the pathlist field
* of 'rel' appropriately.
*
*/
static List *
geqo_prune_rel(RelOptInfo *rel, List *other_rels)
{
List *i = NIL;
List *t_list = NIL;
List *temp_node = NIL;
RelOptInfo *other_rel = (RelOptInfo *) NULL;
foreach(i, other_rels)
{
other_rel = (RelOptInfo *) lfirst(i);
if (same(rel->relids, other_rel->relids))
{
rel->pathlist = add_pathlist(rel,
rel->pathlist,
other_rel->pathlist);
t_list = nconc(t_list, NIL); /* XXX is this right ? */
}
else
{
temp_node = lcons(other_rel, NIL);
t_list = nconc(t_list, temp_node);
}
}
return t_list;
}
/*
* geqo-set-cheapest--
* For a relation 'rel' (which corresponds to a join
* relation), set pointers to the cheapest path
*/
void
geqo_set_cheapest(RelOptInfo *rel)
{
JoinPath *cheapest = (JoinPath *)set_cheapest(rel, rel->pathlist);
if (IsA_JoinPath(cheapest))
rel->size = compute_joinrel_size(cheapest);
else
rel->size = 0;
}
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